Final Report Grant Activity No. 582-5-64593-FY07-20 Analysis of TexAQS II Meteorological Data A report to the Texas Commission on Environmental Quality John W. Nielsen-Gammon Department of Atmospheric Sciences Texas A&M University College Station, Texas May 16, 2008 Contact Information: John W. Nielsen-Gammon, Texas State Climatologist Dept. of Atmospheric Sciences 3150 TAMUS College Station, TX 77843-3150 [email protected] 979-862-2248 979-862-4466 John Nielsen-Gammon Page 1 of 11 May 16, 2008 Executive Summary The purpose of Project 582-5-75693-FY07-20 was to improve the quality of Texas Commission on Environmental Quality (TCEQ) numerical modeling by collecting, quality assuring, evaluating, preparing for data assimilation, and analyzing meteorological information collected during the TexAQS-II field program. Numerous surface and upper air data sets were collected and made available for TCEQ and public access (with documentation) on our TexAQS-II web site, http://www.met.tamu.edu/texaqs2 . In many cases, primary quality assurance was performed by federal agencies or principal investigators, in which case further visual inspection of the data was used to identify outliers. Extensive quality assurance and mixing height estimation was performed on the radar wind profiler network by subcontractor Sonoma Technology, Inc. A related Texas Environmental Research Consortium (TERC) project supported generation of mixing heights from NASA lidar data and collection of other meteorological data into a complete, web-based data set. A series of nudging files were created for meteorological modeling with the MM5 model using the radar wind profiler data and the NOAA shipborne doppler lidar data. The use of nudging in MM5 during a particular test episode (July 30-August 2, 2005) indicated that nudging directly improved the wind fields and indirectly improved the clouds and precipitation. Temperatures were improved in coastal areas where precipitation had a large impact. The use of the Grell cumulus parameterization on the inner 4km grid caused further reductions in clouds and precipitation, with the amounts similar to observations, and it is possible that Grell will be useful in other simulations as well. The possibility of using dual-Doppler wind fields, derived from National Weather Service and mobile SMART radars, in data assimilation was investigated. Artifacts were found in the dual-Doppler wind fields that were attributable to radially-varying errors in the SMART radar velocity fields. Thus, using the SMART radar data for data assimilation is not recommended, though the SMART radar data would be useful for model validation in identifying the inland progression of the Bay Breeze front and the behavior of other meteorological features. Climatological analysis of winds and mixing heights during TexAQS-II revealed that high mixing heights and light winds were generally associated with high ozone. All other things being equal, low mixing heights should be associated with high ozone, but in the cases of Houston, Dallas, and San Antonio, high mixing heights tended to occur when stagnation was prevalent. Low values of the ventilation index, a product of wind speed and mixing height, were associated with high ozone, indicating that the concentrating effect of low wind speeds was more powerful than the diluting effect of high mixing heights. Analysis of individual days showed a range of meteorological conditions, with no single mechanism responsible for high ozone on all the days examined. John Nielsen-Gammon Page 2 of 11 May 16, 2008 1. Introduction Project 582-5-75693-FY07-20 (henceforth, the Project), sponsored by the Texas Commission on Environmental Quality (TCEQ) was initiated in spring 2007 and completed in spring 2008. This summary of the background and objectives of the Project draws heavily upon the original Proposal for Grant Activities and its subsequent amendments. The 2005-2006 Texas Air Quality Study (TexAQS-II) was a major field study conducted in eastern Texas between June 2005 and October 2006, with an emphasis on the Houston and Dallas areas. TexAQS-II attracted scientists from universities and government laboratories across the country. Intensive measurements during selected periods were supplemented by a broader, continuous array of meteorological and chemical measurements. One benefit of this field program is the availability of numerous special observations for assimilation, testing, and evaluation of meteorological models for State Implementation Plan (SIP) development. The purpose of this Project was to improve the quality of TCEQ meteorological modeling by evaluating and providing meteorological data for data assimilation, model verification, and episode characterization. These improvements were in support of the 2005-2006 Texas Air Quality Study (TexAQS-II), the Rules of the TCEQ, the Clean Air Act, SIP development, computer modeling studies, and other goals and requirements. The Project included the following subcomponents: (a) Collection, quality assurance, and reformatting of meteorological data for use in data assimilation (observational nudging) with the MM5 meteorological model, for use in model evaluation, and for use in meteorological analysis (Tasks 3.1 and 3.2); (b) Evaluation of the potential value of Shared Mobile Atmospheric Research and Teaching (SMART) radar data for use in data assimilation with MM5 (Task 3.3); (c) Evaluation of observational nudging files produced by this Project through analysis of MM5 model performance with nudging for a sample episode, and determination of appropriate MM5 base state constant (Tasks 3.4 and 3.5); (d) Characterization of the relationship between upper air meteorological observations and pollution transport during the TexAQS-II field study (Task 3.6). The Project was overseen by John Nielsen-Gammon at Texas A&M University (TAMU). A major portion of component (a) involved quality-control of radar wind profiler and sodar data, together with mixing height estimation. This portion of the work was conducted by Sonoma Technology, Inc., under subcontract to TAMU. Sonoma Technology also carried out the work under component (d). The Project was carried out by TAMU in parallel with a related project funded by the Texas Environmental Research Consortium (TERC) and administered by the Houston Advanced Research Center (HARC). This TERC/HARC project also involved collection and quality-control of meteorological observations during TexAQS-II. The emphasis of John Nielsen-Gammon Page 3 of 11 May 16, 2008 the TERC/HARC project was on data collected during the 2006 field intensive while various other TERC-funded field measurements were being carried out. The TERC/HARC project also had a greater emphasis on broad availability and dissemination of data through development and population of a publicly-available web site. Resources from both projects were used synergistically. For example, all radar wind profiler quality control was conducted under subcontract through this project, while the generation of National Aeronautic and Space Administration (NASA) lidar aerosol mixing heights was conducted under subcontract through the TERC/HARC project. Project personnel at TAMU were assigned to various categories of observations in order that the overall data compilation might be conducted in the most efficient way possible. While this Project is not directly related to other studies, the quality-controlled data sets are likely to receive wide use among scientists involved with analysis of results from the TexAQS-II field program. Thus, many future studies are being assisted indirectly by this Project. 2. Data Collection, Quality Assurance, and Reformatting Many types of data were collected, organized, and in many cases quality-assured in support of this Project and the TERC/HARC project. The complete set of data is listed here. Those data for which collection or quality assurance was funded by TCEQ are indicated by an asterisk. Further descriptions of the data and formatting, as well as the data itself, are available directly on our web site: http://www.met.tamu.edu/texaqs2, and in our final report for TERC Project H84, Development of Databases and Characterization of Meteorological Conditions for the TexAQS II Intensive Period. Surface data: • *NCDC (National Climatic Data Center) hourly surface data, mostly from ASOS (METAR) stations, with some hourly coastal observations added. Common parameters include air temperature and dew point temperature, sea level pressure, wind speed and direction, sky cover, and precipitation. • *TCEQ surface monitoring data for meteorological variables, ozone, and solar radiation. Hourly data was collected for the entire field program, while 5-minute data was collected for the 2006 field intensive and other episodes of interest to TCEQ. • *Buoy and coastal platform data from the National Data Buoy Center (NDBC). The data include wind direction, speed, and peak gusts, sea level pressure, air temperature, dew point temperature, sea surface temperature, visibility, and wave information. • *NOAA (National Oceanic and Atmospheric Administration) Ports data, including five stations in the vicinity of Galveston Bay, reporting wind speed, direction, and gusts, air temperature, water temperature, air pressure, and relative humidity. Some of the data is hourly, some is at 6-minute intervals. Upper air data: John Nielsen-Gammon Page 4 of 11 May 16, 2008 • NCDC upper air data for the United States, Canada, Mexico, and the Caribbean. Most observations are twice a day, including